1. Field of the Invention
The present invention relates to image processing method, which reproduce one image by combining a plurality of devices.
2. Description of the Related Art
In recent years, the opportunities of handling high-dynamic range images (HDR images) having a high dynamic range in objects of the natural world sensed by a digital camera or the like, virtual objects modeled by computer graphics (CG), and the like, are increasing. It is demanded to reproduce such HDR image by a display device or an output device to be faithful to the human subjective vision. In this case, it is expected to use devices such as a projector which can display an image on a large screen and a large-size printer which can make a high-resolution, large-size output, since they can reproduce colors, tones, textures, and the like of real things (objects) and CG objects with a powerful size.
However, the dynamic ranges and color gamuts of these devices do not suffice to reproduce HDR images. For this reason, in order to reproduce HDR images using these devices, tone compression processing and color gamut compression processing called tone mapping have to be applied. Note that the dynamic ranges and color gamuts of the reproduction side devices are desirably as wide as possible so as to reproduce original colors and tones more faithfully.
In consideration of such aspects, since a projector has high white luminance while it projects a small amount of light even in black display, this causes a contrast ratio drop. Especially, since the black luminance rises as illumination is brighter, that is, a so-called black floating phenomenon is inevitable, the contrast ratio and reproduction color gamut are extremely reduced under illumination. Note that a projector is generally called a light-emitting type device since a projection image formed by self emission is detected by the user.
On the other hand, printed matter by a large-size printer does not suffer any serious black floating unlike a projector. However, since this printed matter is a reflecting object, a luminance more than illumination light cannot be obtained, and a sufficient dynamic range cannot be obtained. Note that a printer is generally called a reflection type device since an image is detected by the user based on reflected light of illumination by an image formed on a medium.
To cope with the aforementioned limitations on the luminance and color gamut, attempts have been made to enlarge the luminance and color gamut by stack projection that stacks and displays projection images by a plurality of projectors rather than a single projector (for example, see Japanese Patent Laid-Open Nos. 5-107639 and 2006-145863).